The overall objective of the KATRINA@10 Program is to advance disaster science by including both breadth and depth in a set of interrelated studies. The objective of this project (RP4; DNORS ANALYSIS) is to use new data from a representative sample of pre-Katrina residents of New Orleans?the Displaced New Orleans Residents Survey (DNORS)?to examine outcomes among this population approximately four years after the hurricane. This project will complement investigations in other components of the program, which focus on specific vulnerable populations (RP1, RP2, and RP3) and on overall population change (RP5). A critical need in assessing the social, economic, demographic, and health effects of natural and human-caused disasters? such as Hurricane Katrina?is to obtain population-representative data on the pre-event residents of the affected area. The dispersion of residents in the aftermath of disasters makes this an extremely challenging undertaking, and few studies have been able to collect or assemble such data. Furthermore, few studies have examined post-disaster outcomes over periods longer than one year, leading to a limited understanding of the medium-term outcomes associated with disasters and, in particular, knowledge about which groups are able to adjust to their experiences and which other groups face potentially permanent negative effects. In this project, we will use new data from DNORS to: (1) characterize return migration propensities among individuals and families displaced from New Orleans in the aftermath of Hurricane Katrina; (2) describe the prevalence of psychological distress and disparities by factors such as race; and (3) assess the causal effects of residential displacement and relocation on mental health outcomes. This project will make several important contributions. First, it will provide new information about the residential location of pre-Katrina residents of New Orleans in the four years after the hurricane, a considerably longer period than has been examined previously. Second, this project will be among the first to assess the causal effects of post-Katrina experiences on mental health outcomes using the latest methods for causal inference. Third, we will examine race disparities in post-Katrina outcomes, and will investigate factors associated with black-white differences in return migration, residential location, and mental health. This project's innovation centers on the use of unparalleled new survey data on the medium-term status of pre-Katrina residents of New Orleans and the use of modern methods of causal inference. The results will lead to a better understanding of effects of natural disasters, such as Hurricane Katrina, on the affected populations that will provide valuable information for researchers, policymakers, and the public.